i have the pleasure to go on an annual visit to dornoch so i have had about 25-30 rounds there compared to only one at RCD. accordingly, i am hopelessly biased in favour of dornoch, and not really well placed to make a suitable comparison as i don't know RCD well enough. i would only say about dornoch, though, that it is the very opposite of familiarity breeding contempt. if i could only play one course in my life, i think it would be dornoch.
as for the towns, there is not much comparison. as a previous correspondent mentioned, dornoch is small, quiet, neat and charming. you can walk down the main road and you won't have a car go by for 5 minutes. it probably only has a population of a few hundred. newcastle, by contrast, is a much larger town - 20 times as large? - and hence has a completely different feel.
re the charming irish tom - and at risk of getting into hot water - there is a noticeably different atmosphere in northern ireland compared to the republic (i was there this past weekend, and the trip just confirmed my earlier impressions when i visited, inter alia, RCD and newcastle) the scots may not be a barrel of laughs, but you are not meeting the same people in newcastle that you meet in lahinch/waterville etc.
if any of you are visiting dornoch and want to know of a utterly charming B&B, with a fantastic location, i may be persuaded to part with my knowledge. in my book, it is a great option, much to be preferred to spending lots of money on a big hotel and infinitely superior to the malin house lodge, if you've ever had the misfortune...